The invention relates to a hand-held electrical appliance for personal care or for use as a tool, which appliance has a housing and manually operable actuating means.
Such electrical appliances are known in many versions. Examples are electric shavers and hair dryers but also electric drills etc. Electric shavers usually have a housing of a shape which during use is for the greater part enclosed by the hand of the user and which provides a convenient grip, and an on/off switch which needs to be actuated only at the beginning and at the end of a shaving session. Therefore, it is not necessary for the switch to be held constantly. However, influencing the operation of the shaver during a shaving session is not possible with customary shavers.
Other types of electrical appliances such as, for example, hair dryers and electric drills have a handle, often in the form of a pistol grip. Such appliances frequently have an on/off switch which takes the form of a trigger and which can also be utilized for varying the speed of the drive motor during use. As a result of the use of a trigger-type switch certain limitations are imposed on the designer as regards the design of the electrical appliance, while the user of appliance needs to hold the appliance in a manner which is not always optimal for the task to be performed.
It is an object of the invention to provide another technique of controlling hand-held appliances. To this end, according to the invention, such an electrical appliance is characterized in that the appliance includes at least one force sensor arranged in or on the housing, for supplying a sensor signal which is representative of the force with which the housing is held in the hand of a user, as well as control means for influencing, in response to the sensor signal, at least one parameter relating to the operation of the appliance.
It is to be noted that aspects that play a part in the case of shavers are that different persons generally use a similar shaver in different ways and also that one person does not always handle the shaver in the same way during use thereof. Therefore, there is a need for a shaver which automatically adapts itself to the conditions during a shaving session, in such a manner that irritation of the skin is precluded.
One of the conditions which may vary for each person and for each shaving session, and even during one shaving session, is the force with which the shaver is applied to the skin.
The risk of pain or irritation increases as the shaver is pressed more firmly onto the skin. In accordance with the invention this effect is precluded or at least mitigated by utilizing the fact that, as is evidenced by tests, there is a relationship between the force with which a shaver is held and the force with which a shaver is applied to the skin in the sense that gripping the shaver more firmly also results in more force being exerted on the skin surface to be shaved. Thus, when the appliance is being normally held and operated, the user""s hand will continuously exert force on the sensor, but the magnitude of that force may vary.
The invention will be described in more detail hereinafter with reference to the accompanying drawings.